<template>
  <view>
     <view class="scroll-view-container">
       <!-- 左侧 -->
       <scroll-view scroll-y="true" :style="{height:wh+'px'}" class="left-scroll-view">
        <block v-for="(item,i) in cateList" :key='i'>
              <view :class="['left-scroll-view-item',i === active ?'active':'']"
               @click="activeChange(i)"
              >{{item.cat_name}}</view>
        </block>
          
       </scroll-view>
       <!-- 右侧 -->
       <scroll-view class="right-scroll-view" scroll-y :style="{height: wh + 'px'}" :scroll-top="scrollTop">
         <view class="cate-lv2" v-for="( item2,i2) in cateLevel2" :key='i2'>
           <view class="cate-lv2-title ">/{{item2.cat_name}}/ </view>
           <view class="cate-lv3-list">
             <view class="cate-lv3-item" 
             v-for="( item3,i3) in item2.children" :key='i3'
             @click="gotoGoodsList(item3)"
             >
               <image :src="item3.cat_icon" mode=""></image>
               <text>{{item3.cat_name}}</text>
             </view>
           </view>
         </view>
         
       </scroll-view>
     </view>
  </view>
</template>

<script>
  export default {
    data() {
      return {
         // 窗口的可用高度 = 屏幕高度 - navigationBar高度 - tabBar 高度
         wh: 0,
          // 分类数据列表
          cateList: [],
          active:0,
          // 二级分类列表
          cateLevel2: [],
          scrollTop:0
      };
    },
    onLoad() {
       // 获取当前系统的信息
       const sysInfo = uni.getSystemInfoSync()
        // 为 wh 窗口可用高度动态赋值
       this.wh = sysInfo.windowHeight
       // 调用获取分类列表数据的方法
         this.getCateList()
    },
    methods:{
        async getCateList() {
          // 发起请求
          const { data: res } = await uni.$http.get('/api/public/v1/categories')
          console.log(res)
          // 判断是否获取失败
          if (res.meta.status !== 200) return uni.$showMsg()
          // 转存数据
          this.cateList = res.message
            // 为二级分类赋值
            
           this.cateLevel2 = res.message[0].children
        },
        activeChange(i){
          this.active=i
          //二级分类重新赋值  (重要一步 切换也可以跳)
         this.cateLevel2= this.cateList[i].children
         this.scrollTop=this.scrollTop===0 ?1 :0
        },
        // 点击三级分类项跳转到商品列表页面
        gotoGoodsList(item3) {
          uni.navigateTo({
            url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
          })
        }
        
    }
  }
</script>

<style lang="scss">
.scroll-view-container{
  display: flex;
  .left-scroll-view{
    width: 120px;
  }
  .left-scroll-view-item {
        line-height: 60px;
        background-color: #f7f7f7;
        text-align: center;
        font-size: 12px;
        // 激活项的样式
             &.active {
               position: relative;
               background-color: #ffffff;
               // 渲染激活项左侧的红色指示边线
                       &::before {
                         content: ' ';
                         display: block;
                         width: 3px;
                         height: 30px;
                         background-color: #c00000;
                         position: absolute;
                         left: 0;
                         top: 50%;
                         transform: translateY(-50%);
                       }
             }
   }  
  
}
.cate-lv2-title{
  font-size: 12px;
  font-weight: blod;
  text-align: center;
  padding: 15px 0;
}
.cate-lv3-list{
  display: flex;
  flex-wrap: wrap;
  .cate-lv3-item{
    width: 33.33%;
    display: flex;
   flex-direction: column;
   justify-content: center;
   align-items: center;
   margin-bottom: 10px;
      image{
          width: 60px;
          height: 60px;
        }
        text{
          font-size: 12px;
        }
  }
}

</style>
